Electrical heating device



M. S. PARNELL-SMITH.

ELECTRICAL HEATING DEVICE. APPLICATION FILED 0cm I1,I920I iatemed Mar.7, 1922,

UNITED STATES PATENT OFFICE.

MICHAEL SIMEON PARNELL-SMITH, OF LONDON, ENGLAND, ASSIGNOR T FRANKSMITH, OF LONDON, ENGLAND.

ELECTRICAL .HIEATING DEVICE.

Specification of Letters Patent.

Patented Mar. '7, 1922.

Application filed October 11, 1920. Serial No. 416,077.

. To all whom it may concern:

Be it known that I, MICHAEL SIMEoN PARNELL-SMITH, a subject of the Kingof England, residing at London, England, have invented certain new anduseful Improvements in Electrical Heating Devices, of which thefollowing is a specification.

This invention is for improvements in or relating to electrical heatingdevices and-has for its object to provide a device in which theefficiency shall be considerably greater than in those hithertoemployed.

According to the present invention a unit, for use as an electricalheating device, comprisesan element, such for example as a resistancewire, which is to be heated by the passage through it of an electriccurrent and is enclosed in a gas-charged chamber, such for example as achamber charged with inert gas such as nitrogen or argon.

Preferably the chamber is formed of a heat-conducting material such ascopper or brass, and in one form of the invention the chamber iscombined with a jacket. In the space between the jacket and the chambera fluid to be heated may be passed, preferably in theiorm of a thinfilm.

The presence of an inert gas in a container enclosing an electricfilament is known in the manufacture of electric incandescent lamps, butthe present invention does not include lighting elements.

One preferred form of the invention will I now be described by way ofexample only with the aid of the in which- Figure 1 is a central sectionthrough the heating-unit; and

igure 2 on a smaller scale is a section on the line II-II of Figure 1.

Like reference numerals parts in the drawings.

A aliollow metal cylinder 1, for example of copper or brass, ispreferably corrugated as shown more particularly in Figure 2 with thecorrugations running parallel with the direction of its length. Withinand near each end, and also centrally within the cylinder 1, are rings 2of fireclay, procelain or some other insulating and refractory material.

Rods 3 of similar material are engaged at their ends, which are reducedas shown, within recesses in the rings 2 and are held firmly therein. Aresistance wire 4 of maaccompanying drawings indicate like terial suchas is commonly used for electric heaters, for example nickel-chromium,or other high-resistance wire, is wound in .series round the severalrods 3, this wire being indicated diagrammatically in the drawing.

The ends of the cylinder 1 may be left uncorrugated and are closed bycaps 5 and 6 respectively. The cap 6 may be conven iently screwed on tothe end of the cylinder 1 and is formed with an orifice normally closedby a screw-plug 7. The plug T, when in position, constitutes one ofthree equidistantly-spaced feet, the other two, indicated at 8, beingformed by casting or otherwise on the outer surface of the cap 6. In thecap 5 there is a gas-cock 9 for the admissionof gas to the cylinder 1.The cap 5 may be secured in any convenient manner, for example bywelding to the cylinder, and when the parts are assembled with the plug7 inserted in position and the cock 9 closed the cylinder issubstantially gas-tight.

The cylinder 1 is conveniently contained within a cylindrical chamber orjacket 10, the walls of which are spaced a small distance from thewallsof the cylinder 1 so that iiuid admitted to the jacket through theinlet-pipe 11 will flow as a comparatively thin film through the jacketover the surface of the tube 1 to the outlet-pipe 12. The latter isdisposed above the cap 5 so that the liquid will cover the cap beforepassing to the outlet.

The upper end of the cylinder 10 is closed by a cap 13 held in positionby set-screws 14. An orifice in the cap 13 permits of the insertion of adouble-poled terminal of which the two conducting portions 15 and 16 areinsulated from one another by the insulating cylinder 17. The twoextremities of the wire 4 are connected to the members 15 and 16respectively and the latter, outside the cap 13, are connected withelectric supply mains 18.

The cylinder 10 may be formed with lugs 19 by which the apparatus as awhole may be secured to a support by means of screws or the like.

The cylinder 1 comprises a substantially airtight chamber enclosing theresistancewire and this chamber is charged with an inert gas such asnitrogen or argon or other gas which will have no appreciable chemicalaction either on the resistance-wire or the material of the chamberenclosing it in either till heated or cold condition. In order to chargethe cylinder 1, gas is admitted under pressure through the cock 9 withthe plug 7 removed. The gas passes out through the orifice opened by theremoval oi the plug and sweeps the contained air before it. Thisoperation may be repeated several times until the air has beencompletely or substantially completely replaced by the gas so that, forexample not more than about 1% of air remains in the chamber. The plug 7is then replaced and the cock 9 closed which seals the cylinder inasubstantially gas-tight man- Alternatively the filling of the cylinder1 may be assisted by evacuating it before the admission of the l' it-hthe construction illustrated, water or other liquid to be heated may bepassed through the space between the jacket 10 and the cylinder 1 bymeans of the pipes 11 and 12, the liquid flowing in a comparatively thinfilm over the surface of the corrugated cylinder 1, thereby becomingheated during its passage through the jacketed space and issuing from anoutlet-pipe as hot water, the temperature spending inter she, as isusual in such. apparatus, upon the rate 01 Flow and the thickness of thefilm of water and the temperature to which the heating-element israised.

A tap for controlling admissionot liquid to the pipe 11 preferablycombines in it a switch for the circuit including the mains 18. The tapmay be of the usual plug type, the operating-handle of which is extendedin the form of a blade oi, for example, a knifeswitch so that the switchwill not be closed to energize the resistance-wire lunless the fluid isalso the same time admitted to the jacket The provision of such combinedtap and switch, however, is-not essential to the present invention.

It is anticipated that large units of similar construction may beemployed with boilers of larger dimensions and that, with the use ofsuiliciently large units, steam-boilers for the production of steam formotive power may be constructed.

The unit may be employed as an ordinary heating-unit for a room or thelike without the use of the jacket 12, the outer of the cylinder 1constituting a source-oi radiant heat.

l-leating-elements enclosed in a similar manner in a gas-charged chamberor tube may be employed in electrically-heated kettles, irons and otherdomestic articles, the form of the gas-charged chamber and theheating-element being suited to the particular purpose to which it to beapplied.

It will be appreciated that there are many other uses to which a unitembodying the principles of the present invention may be applied withoutdeparting from the spirit of the invention and that the unit, illus- 2.An electric combination an element which is to be heated by the passagethrough it of an electric current, a chamber which-encloses said elementand is filled with an inert gas, a substantial part of the heatingsurface of said chamber being of irregular form.

' heating unit comprising in An electric combination an element wliic isto be heated by the passage through it of an electric current, and agas-charged chamber which encloses said element and is formed ofheatconducting material, said chamber having a cover permitting theinsertion and removal of: said element.

4:. An electric heating unit comprising in combination an element whichis to heat .ed by the passage through it of an electric current andgas-charged chamber which encloses said element, is -formed ofheatconducting material and has corrugated walls.

5. An electric heating unit comprising in combination an element whichis to be heated by the passage through it of an electric current. agas-charged chamber enclosing said element, a jacket surrounding saidchamber and means to pass a fluid to be heated through the space betweenthe chamber and the jacket, said jacket having a removable closurepermitting the insertion of said chamber.

6. An electric heating unit comprising in combination an element whichis to be heat-- ed by the passage through it of an electric current, agas-charged chamber enclosing said element and means to pass a fluid tobe heated in a comparatively thin film of irregular depth over the outersurface of said chamber.

'7. An electric heating unit comprising in combination an element whichis to be heated by the passage through it of an electric current, achamber enclosing said element which chamber is closed by means of agas-cock near one end, and a removable plug near the opposite end.

8. An electric heating unit comprising in combination an element whichis to be heated by the passage through it of an electric current, acylindrical gas-charged chamber enclosing said element, a secondcylindrical chamber having means to permit of the gas charged chamberbeing entered and enclosed the passage through the space between the twochambers of a liquid to be heated.

9. An electric heating unit comprising in combination an element whichis to be heated by the passage through it of an electric current, acylindrical gas-charged chamber enclosing said element, a secondcylindrical chamber within which the gas-charged chamber can be enteredfrom one end to be enclosed therein with a space between the walls ofthe two chambers, conduits entering said second chamber at the bottomand top thereof to serve as inlet and outlet conduits for the passagethrough the space between the two chambers of a liquid to be heated, aremovable cover for said second chamber, a plug sealed in the cover ofthe gas-charged chamber and extending through the cover of said secondchamber, and terminals carried in said plug to connect electrical supplymains outside said second chamber with the element to be heated withinthe gas-charged chamber.

In testimony whereof I afiix my signature.

MICHAEL SIMEON PARNELL-SMITH.

